Plastic process for making printing plates



Dec. 31, 1940. w KE Y ETA, 2,227,139

PLASTIC PROCESS FOR MAKING PRINTING PLATES Filed Oct. 18, 1957 PatentedDec. 31, 1940 UNITED STATES PATENT OFFICE 1 PLASTIC PROCESS FOR MAKINGPRINTING PLATES chusetts I Application October 18, 1937, Serial No.169,652

4 Claims.

This in ention relates to a thoroughly hardened plastic plate having asurface of different construction from the base and being of a special 5value when used as a printing plate.

The principal objects of this invention are to provide such a plate witha strong back which is very hard and resistant to wear; to provide a topsurface cohering to the top surface of the back in such a manner thatthey are entirely inseparable from each other; to provide a frontsurface which can be provided with a design in intaglio without havingto use pressure or a high heat in the formation of the surface; toprovide such a surface by use of moderate heat for the purpose only ofhelping to harden that surface in certain areas only; to provide aconstruction in which the durability for making impressions will begreatly increased over any other plate whether. of zinc, lead, or thelike, and to the surface composed of a non-metallic material all over itand the utilization of reflection of light from that surface for thepurpose of making the intaglio design;

Fig. 3 is asectional view showing the carrying out of the process, and

Fig. 4 is a modification similar to Fig. 3 showing the use of aphotographic negative or decalcomania transfer.

A plate can be made in accordance with this invention which is entirelyhard and durable for use in publishing houses and which is capable ofbeing'used in advertising where its practical indestructability is ofvalue. A plate is shown comprising a solid back ID of thickness, orthereabout, formed of entirely non-metallic material compounded in sucha manner that it would not only be strong as regards blows directlyapplied to it but also as regards long continued use of it as 50 aprinting plate.

As a printing plate,.t-he front surface I! is of fine texture but onecapable of resisting high pressure in the printing press and extremely Iably of asbestos and Portland cement, or the like. The two materials,with water, are mixed in any usual way, dried to a certain extent, andthen compressed to form a flat base.

On the top of the base HI is provided a printing 5 surface. Thisprinting surface is made of a filler of approximately 60% English clayand 40% Paris white, by weight, to which is added about 6% additionalanimal glue in a dissolved state. English clay is a granitic andfelspathic non-vit- 1o rc-us yellowish white natural clay. The glueconstitutes a temporary binder to bind together the English clay andParis white either wet or dry. For certain purposes, if twenty-fivepounds of w this material were used, five gallons of hot water 15 wouldbe added to it. This mixture is not ready for use at this time because,instead of five gallons of cold water which would have a tendency to setthe mixture, five gallons of hot water and 10% in volume of a. syntheticvarnish, as for 0 example phenol, formaldehyde, and tung oil, are addedto the filler. Together they constitute a gum which can be mixedthoroughly by a paint ixer, for example. It is to be understood thatthese latter materials except the base may be of 25 any metallic ornon-metallic materials suitable for that purpose. The animal glue isdissolved to constitute a temporary binder.- The synthetic varnish"doesnot contain any metal or alloy.

The preferred method of manufacture is to lay so the paste on the blockl0 about /5" thick, then let it dry and set for five days. During thistime the powder and glue have dried but the synthetic varnish or gum hasnot dried to its final state but is still of such a nature as to admitof its being sanded down to make a smooth, even surface.

Now the design is applied either by hand. decalcomania. transfer, orphotographic negative, or stencil i3, or any standard transfer, or thelike, may be used. Those parts which are to be in intaglio are coveredby some reflecting surface H while those not to be changed are leftexposed. The protection is in the form of a reflecting surface on allthe surfaces to be eventually in intaglio but this reflecting surfacemay be coated with black paint, or the like. Now heat is applied by theuse of a light or heating unit at a temperature of not more than 250 F.whichhardens and sets the gum which acts now as a binder so that thewhole mixture becomes hardened. The light or heat is allowed to play onthe whole surface and it is obvious that that light or heat which playson the protected surnarily.

faces will be reflected back, as by a mirror, and thelight or heat whichplays on the unprotected surfaces will be absorbed by the materialexposed at those points. At about that time the synthetic varnish or gumexposed to the heat or light will become plastic and comparativelyinsoluble.

The next step is to remove the reflecting coverings on the surfacemechanically and then the under surfaces and material can be removed bythe application of hot water, or the like to provide an intaglioprinting surface. To remove surfaces from the design water can besprayed on from below, the plate being held with the printing surfacedown.

A photographic negative l3, decalcomania transfer, or stencil can beused.

It is found in practice that this plate and its surfaces are durable fora great many impressions, up to 400,000 for example, so that in spite ofits lower cost of manufacture compared to an acid etched metallic plateused extensively in this field it hasqualities commending it inpreference to the orthodox. printing plate now used.

Another important feature is the elimination almost entirely of thepress make-ready employed heretofore in printing plants, for practicallyevery plate produced. This is very expensive because it requires themost expensive workman in the crew and practically nothing else can bedone in regard to this plate while'he is working on it. It frequentlytakes many hours, which involves an important delay. In other .words,the plate is ready when this process is finished and need not betampered with ordi- The make-ready also involves considerable expensenotrequired in this process.

As a matter of fact, the hard and tough body is not reshaped after it isall made. Of course, the reason for this is the use of cement andasbestos which is finely mixed with the Portland cement.

Inplace of phenol, formaldehyde and tung oil used to form the gum, otherwell known varnishes and the like can be used, but this is a verysuitable one for use in this process.

Having thus described our invention and the advantages thereof, we donot wish to be limited to the details herein disclosed, otherwise thanas set forth in the claims, but what we claim is:

1. As an article of manufacture, a printing plate having a durable baseand a printing surface of mixed non-metallic ingredients including atemporary binder and a gum-forming material, for the purpose described.

2. As an article of manufacture, a printing plate having a durable baseand'a printing surface of mixed non-metallic ingredients includingEnglish clay, Paris white, animal glue, and a gum-forming material. I

3. As an article of manufacture, a printing plate having a durable baseprovided with a printing surface of mixed non-metallic ingredientsincluding English clay, Paris white, animal glue, and a syntheticvarnish having an intaglio design thereon.

4. A non-metallic printing plate having a hard non-metallic durablebase'of material thickness, a. relatively thin layer adhering theretocomprising English clay, Paris white, a dissolved animal glue, and asynthetic varnish having an intaglio design thereon.

JOHN W. KELLY. DANIEL J. KELLY.

